During open heart surgery and in some emergency cardiopulmonary situations, it is necessary to have some means for pumping the blood and some means for oxygenating the blood to replace or support the patient's cardiopulmonary functions. Mechanical substitutes for doing this can operate by taking blood from the patient's venous system and oxygenating it by dispersing it over one face of a membrane area and exposing the opposite face to an atmosphere of pure or nearly pure oxygen. After the blood absorbs oxygen in this environment, it is forced by means of a pump into the arterial system of the patient.
Prior art extracorporeal device technology has used individual devices for the functions of pumping blood and oxygenating blood. For example, a pump would be used in conjunction with an oxygenator. Typically, these devices are connected together in an extracorporeal tubing loop to receive venous blood from the patient and return arterial blood back to the patient. One of the problems with these types of devices, such as that shown in U.S. Pat. No. 3,183,908, has been that large amounts of blood are required to prime the oxygenator, the pump, and the tubing between the oxygenator and the pump.
Some attempts have been made to incorporate the pumping and oxygenation functions in a single device. For example, U.S. Pat. No. 3,841,837 discloses a blood oxygenator or dialyzer that achieves enhanced transfer through rotation of a cylindrically mounted membrane placed eccentrically inside a stator housing. Blood flows in the annular space between the rotor and the stator. Rotation causes a pumping action, thus causing pumping and oxygenation to occur simultaneously. All of these prior art devices have required relatively large amounts of fluid to prime the pump and oxygenator. There have also been difficulties with the safety and ease of use by the perfusionist. Furthermore, these devices can be quite costly to manufacture.